Generalization in foreign accent adaptation is predicted by similarity of segmental errors across talkers

Abstract

Comprehension of foreign-accented speech improves with exposure. Previous work demonstrates that listeners who adapt to accented talkers generalize that adaptation to other accented talkers—exposure to multiple talkers of the same accent facilitates comprehension of a novel talker of that accent (e.g. Bradlow and Bent, 2008) and exposure to multiple novel accents facilitates comprehension of yet another novel accent (Baese-Berk et al., 2013). To examine possible theories of accent adaptation and generalization, we created a new dataset of phonetically transcribed accented speech produced by the training and test talkers used as stimuli in studies of accented speech generalization (Bradlow and Bent, 2008; Baese-Berk et al., 2013). Using this dataset, we computed the (cosine) similarities between accented talkers in a multidimensional accent space defined by the rates at which talkers made different segment-level phonetic errors. Results show that similarity in this space accounts for all significant differences between training conditions in Bradlow and Bent (2008) and Baese-Berk et al. (2013): training conditions including more of the same types of phonetic errors as those of the test talkers led to better test talker comprehension. These results suggest that prior accent generalization results are compatible with simple, segment-error driven theories of adaptation.